Geological map - abbreviation - i.g.

The best I could find.
https://search.yahoo.com/yhs/search;_ylt=AwrXmf27ww1by1MAMZcPxQt.;_ylc=X1MDMjExNDcwMDU1OQRfcgMyBGZyA3locy1wdHktcHR5X3dlYXRoZXIEZ3ByaWQDamRpcnozT3FUVTZ3VE9BQ2t0WlRzQQRuX3JzbHQDMARuX3N1Z2cDNgRvcmlnaW4Dc2VhcmNoLnlhaG9vLmNvbQRwb3MDMQRwcXN0cgMgaS5nLiBtZWFuaW5nIARwcXN0cmwDMTQEcXN0cmwDMzAEcXVlcnkDaSUyMGclMjBtZWFuaW5nJTIwYWJicmV2aWF0aW9uBHRfc3RtcAMxNTI3NjI4NzkzBHVzZV9jYXNlAw--?p=i+g+meaning+abbreviation&fr2=sa-gp-search&hspart=pty&hsimp=yhs-pty_weather&param1=20180505&param2=54d7d8fe-9e1d-9f5c-2b00-fb1885a96280&param3=weather_xp_1.15~US~&param4=~Chrome~in+geology+what+does+i.g.+meaning~D41D8CD98F00B204E9800998ECF8427E&type=weaff_0_cr

BTW, be careful in looking for your answer. There are sites that are virus' linked.

Thank you for your effort, but there does not seem to be an answer there...
I wonder if i.g. in geological maps legends can be somehow related to "igneous" (rocks), but I could not find any proof (they use "ig" abbreviation meaning "igneous", but here it is "i.g." consistently...

I guess

https://www.urbandictionary.com/define.php?term=Ig

If there is one thing I am sure about, it's "they don't write "i guess" in geological maps". If there is a person who is well versed in geology/geological maps, I would appriciate their help.

farmerman would know...

That's the best I could find. Sorry for trying to help.

If this is the document that you are trying to read, that is likely to be the case:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760019531.pdf

"At present we are trying to put all the information about igneous rocks obtained from the interpretation of air photo, field work, published and unpublished reports and maps, on the ERTS photos, with a scale of 1/500,000, and make a map of the igneous rocks of Iran."

What a faded document. Almost hurts your eyes to try to read it.

Thank you, that one I have also found, mine is slightly different but similar.
Based on the structure of the legend, I think now - could it mean "including groups" (or something else starting with "g")? This "i.g." stands at the "main" unit of the legend, which then below is shown to include smaller "sub-units".
Anyway, thanks to everyone who replied!

Thank you very much for your help and replies, which breathed life into this previously unanswered topic.

Im a geologist and While we have lots of additions on maps that indicate source data and language base for fild copies. Ive actually never seen the terminology source (like I. G.) on a final published map, (since most geo maps are produced by that country's geological Survey.

It used to mean Indo Germanic., but I have no references in any of my sources that even refer to its use.
So, I cant much help.
But your thought that it could mean "included groups" does make some sense
Is the abbreviation in the actual legends of the maps?